This invention relates in general to electrical fuses and more particularly to an electric fuse which contains an asymmetrical link to provide superior operating characteristics.
It is well known to those skilled in the art that fusible links which are commonly used in fuses are employed in a great number of applications.
Essentially, a fusible link may consist of a ribbon of relatively thin metal commonly copper or silver which is disposed singly or in multiples between two end terminals or between two end caps. The link will melt when an excess of current based on the rating of the link is passed through the link and hence such links afford circuit protection. The state of the fuse art is such that the prior art is replete with many patents and articles depicting fuses of different types wich are employed for different circuit operation and different circuit conditions. A major objective in the design of many fuses is for a fast reaction time which means that the fuses should respond very rapidly to a current which exceeds the rating of the fuse. In this manner, the fuse will properly protect the associated circuit.
Another problem which as been faced by fuse designers is the suppression of high peak recovery voltages. As one knows, a fuse may be protecting an inductive circuit, and hence when current is interrupted in such a circuit, a large voltage transient is produced where the magnitude is proportional to the inductance as multiplied by the rate of change of current with respect to time. This is a common problem in current limiting fuses.
Such peak voltages can be of the order of magnitude of thousands of volts. Hence fuse devices which operate in such environments require arc quenching means to suppress such arcs in order to further prevent these large voltages from affecting the circuit or preventing proper fuse operation. Therefore, as one can ascertain, the problem of arc suppression is incompatible with the problem of reaction time. As one can see, the shorter the reaction time, the higher the arc voltage provided in an inductive circuit. Hence fuse designers have been cognizant of these factors and have proposed various designs to accommodate both requirements.
It is, therefore, an object of the present invention to provide a fuse link construction which is capable of reacting in a relatively rapid manner to an overload condition and to give superior speed and current limiting capability while further suppressing the attendant peak recovery voltage produced during fuse operation.